Header mask signal generating track jump method for a recording medium

ABSTRACT

A track jump method for an optical recording/reproducing medium is provided. In the track jump method, once a track jump command is input, a track jump operation is held until a falling edge of a header mask signal is detected. The track jump starts at the falling edge of the header mask signal and ends before a rising edge of the header mask signal so that a TZC signal is not influenced by a header during the track jump. Therefore, the track jump can be exactly and stably performed. In particular, when the track jump command is input, a PLL of a wobble signal is inhibited, and a PLL-wobble signal is held to a previous value obtained before the track jump is performed, during the track jump, or a header mask signal is generated using a read channel signal which is not influenced by a wobble period, until a wobble signal becomes stable after a trackjump. During a normal servo, a header mask signal is generated using a PLL-wobble signal to mask a header area. Therefore, a header area coming first after the trackjump is completed can be stably masked, thereby preventing a system from being unstable due to a header during the track jump.

This application is a Continuation of application Ser. No. 09/617,088,filed on Jul. 14, 2000 now U.S. Pat. No. 7,012,861, the entire contentsof which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a track jump on an optical recordingand reproducing medium, and more particularly, to a method of performinga trackjump without being influenced by a header.

2. Description of the Related Art

Generally, an optical recording medium system, i.e., an opticalrecording and reproducing apparatus, employs an optical disc as arecording medium and reproduces data recorded on the disc or recordsdata on the disc.

A tracking servo in the optical recording and reproducing apparatusdetects a tracking error signal corresponding to a beam tracing stateand shifts an objective lens and the body of an optical pickup based onthe signal to modify the location of a beam and follow up apredetermined track.

At this time, a track jump is essential to a time search or a variablebit rate (VBR) operation. When the number of tracks to be jumped issmall, a track is searched for using a tracking actuator.

FIG. 1 is a block diagram of a typical optical recording/reproducingapparatus capable of performing a track jump. An optical pickup (P/U)102 makes a light beam focused on an objective lens be put on a signaltrack on an optical disc 101 under control of a servo controller 106 andfocuses light reflected from a signal recording side on the objectivelens. Then, the P/U 102 makes the light focused on the objective lens tobe incident on an optical detector (not shown) to detect a focus errorsignal and a tracking error signal.

The optical detector is composed of a plurality of optical detectingdevices. An electric signal proportional to the amount of light obtainedfrom the optical detecting devices is output to a radio frequency (RF)and servo error generator 104. The RF and servo error generator 104detects an RF signal for reproduction of data and a focus error signalFE and a tracking error signal TE for servo control, from the electricsignal output from the optical detector. The RF signal is output to adecoder 105 for reproduction, and servo error signals, i.e., FE and TE,are output to the servo controller 106. A control signal for recordingof data is output to an encoder 103.

The encoder 103 codes data to be recorded in a recording pulse having aformat required by the optical disc 101 and records the coded data onthe optical disc 101 through the P/U 102. The decoder 105 reconstructsoriginal data from the RF signal.

A host such as a personal computer may be connected to the opticalrecording/reproducing apparatus. The host transmits arecording/reproducing command to a microcomputer 111 through aninterface unit 110 of the optical recording/reproducing apparatus,transmits the data to be recorded to the encoder 103 and receives thereconstructed data from the decoder 105. The microcomputer 111 controlsthe encoder 103, the decoder 105 and the servo controller 106 accordingto the recording/reproducing command of the host.

For the interface unit 110, an advanced technology attached packetinterface (ATAPI) unit is typically used. The ATAPI is a specificationfor interfacing an optical recording/reproducing apparatus such as acompact disc (CD) drive or a digital versatile disc (DVD) drive with ahost. The ATAPI is proposed for transmitting data decoded in the opticalrecording/reproducing apparatus to the host. The ATAPI converts thedecoded data into a protocol in a packet format which can be processedby the host, before transmission.

The servo controller 106 processes the focus error signal FE to output adriving signal for focusing control to a focus servo driver 107 andprocesses the tracking error signal TF to output a driving signal fortracking control to a tracking servo driver 108.

The focus servo driver 107 drives a focus actuator within the P/U 102 tothereby shift the P/U 102 up or down so that the P/U 102 can follow upthe rotating optical disc 101 with an up-and-down motion.

The tracking servo driver 108 drives a tracking actuator within the P/U102 to thereby shift the objective lens of the P/U 102 in a radialdirection so that the location of a beam can be modified, and apredetermined track is followed.

When the optical disc 101 is a rewritable disc, particularly, a digitalversatile disc random access memory (DVD-RAM), since there is noinformation on an initial disc, disc control and recording cannot beperformed. To overcome this problem, disc tracks are formed on land andgrooves to allow information to be recorded on each track, and sectoraddresses and control information for random access and rotation controlare separately recorded on the disc, thereby allowing tracking controlto be executed on a blank disc on which an information signal is notrecorded on. The control information may be recorded in the beginning ofeach sector by pre-formatting a header area or may be recorded inwobbling shape along each track. The wobbling means that information tobe applied to a disc by modulating a certain clock, for example,information on a certain location and information on the rotationalspeed of a disc, is supplied to the power of a laser diode, so thatcontrol signal is recorded at the boundary surface between tracks by avariation of the light beam of the corresponding laser.

For example, in the case of a DVD-RAM, a header area which ispre-formatted at the beginning of each sector is composed of four headerfields HD1 through HD4, as shown in FIG. 2( a). The header fields HD1/2and the header fields HD3/4 are offset from the center of a track in anopposite direction to each other. In other words, the phase of theheader fields HD1/2 is reverse to the phase of the header fields HD3/4,and the phase of a tracking error signal detected from the header fieldsHD1/2 is reverse to the phase of a tracking error signal detected fromthe header fields HD3/4. In addition, referring to FIG. 2( a), it can beknown that the track boundary of a user area in which actual data isrecorded has a wobbling shape.

Accordingly, a header mask is put on a header area, as shown in FIG. 2(b), and a track error signal is held during a track servo to preventdeviation from a track center.

To generate a header mask signal indicating a header area, the headerarea should be detected first.

Various methods can be used for detecting the header area, and one ofthem is using a wobble signal as shown in FIGS. 2( a) through 2(c).

More specifically, since the number of wobble signals in each sector isfixed, the header area is detected by counting the number of wobblesignals. Since a wobble signal may not be detected due to a defect on adisc, the header area is detected by counting clocks, i.e., phase lockedloop (PLL)-wobbles, in which wobble signals actually recorded on thedisc are subjected to a PLL, as shown in FIG. 2( c), and a header masksignal (H/M) is generated as shown in FIG. 2( b).

For example, PLL-wobble signals are counted starting from a fallingpoint of a previous header mask signal. When a predetermined number hasbeen counted, it is determined that a header area begins, and thus aheader mask signal is generated.

Since a wobble signal is not recorded in the header area, no wobblesignal is detected from the header area. Accordingly, a wobble isomitted in a header area. When a wobble signal detected is subjected toa PLL without considering the omission of a wobble signal, a PLL-wobblesignal elongates. This causes a header mask signal to be generatedlagging behind an actual header area, that is, generation of a headermask signal is delayed.

To solve this problem, a PLL-wobble signal is held with a tracking errorsignal in a header area.

When a track jump command is input, the RF and servo error generator 104detects an RF signal (shown in FIG. 3( d)) and a tracking error signalTE (shown in FIG. 3( a)) through the P/U 102 in a state in which only afocus servo is on, and simultaneously, the servo controller 106generates a kick pulse (or a jump pulse) as shown in FIG. 3( c). Thekick pulse is applied to the tracking actuator through the trackingservo driver 108. When the kick pulse is applied to the trackingactuator, the speed of the tracking actuator increases, and theobjective lens of the tracking actuator is pushed toward a track jumpdirection by acceleration of the tracking actuator.

At this time, a brake pulse is applied to the actuator at a zero crosspoint of the tracking error signal for a predetermined brake time toreduce the speed of the actuator. In other words, the tracking actuatoris accelerated by the kick pulse and then decelerated by the brakepulse. The brake pulse is an inverted one of the kick pulse and isgenerated to stably stop the actuator at an exact desired location. Whenthe brake time previously set has elapsed, a tracking servo is turnedon.

A track zero crossing (TZC) signal which is turned on/off at the zerocross point of the tracking error signal TE, as shown in FIG. 3( b), isused as a reference signal for determining a kick pulse, brake pulse anda brake on time during a track jump. In other words, the TZC signal isused as a reference signal when determining at what point the brakepulse will be generated after the kick pulse is generated.

When the tracking actuator passes a header area (see the circled part inFIG. 3( a)) during a track jump, the TZC signal may be generated priorto or behind a desired location due to a header, or one more pulse ofthe TZC signal may be generated as shown in the circled part in FIG. 3(b).

Accordingly, when the optical disc 101 includes header areas like aDVD-RAM, a problem may occur due to a header area during a track jump.

In other words, when the TZC signal is generated prior to or behind adesired location, or when more pulses of the TZC signal than is desiredare generated, the TZC signal goes beyond a location where it isoriginally supposed to be generated, and a kick time, brake time and aservo on time become irregular so that a track jump cannot be exactlyand stably performed.

In addition, as shown in FIG. 4( a), when a track jump is performeddepending on a track jump command, a wobble signal may not be detectedsince the tracking actuator crosses tracks.

Since a wobble signal is omitted, as shown in FIGS. 4( d) through 4(g),during a track jump, a PLL-wobble signal elongates. A wobble signalrecorded on an actual disc is shown in FIG. 4( d). The part in thecircle of FIG. 4( d) is enlarged in FIG. 4( f). The PLL-wobble signal,in which a wobble signal detected as shown in FIG. 4( d) is subjected toa PLL, is shown in FIG. 4( e). The part in the circle of FIG. 4( e) isenlarged in FIG. 4( g). A header area is indicated through an RF signalof FIG. 4( b). The RF signal corresponding to the header area is alwayshigher than a certain level. The RF signal has the same phase withrespect to the header fields HD1/2 and the header fields HD3/4.

As shown in FIG. 4( c), a rising point of a header mask signal, that isgenerated after a track jump, lags behind the actual location of aheader area. Consequently, the header area cannot be masked so that atracking error signal cannot be held in the header area. Accordingly,the tracking error signal becomes larger as shown in the circled part ofFIG. 4( a), and the actuator follows up the header.

When the actuator follows up the header, track slippage may occur, and atrack servo becomes unstable due to a change in a discrete track error.The unstable track servo deteriorates recording and reproducingcharacteristics.

In other words, a header area that comes first after a track jump isperformed cannot be stably masked so that the system can be unstable dueto a header during the track jump.

SUMMARY OF THE INVENTION

to solve the above problems, a first object of the present invention isto provide a method for performing a track jump without being influencedby a header area.

A second object of the present invention is to provide a trackjumpmethod of inhibiting a wobble signal from being subjected to a phaselocked loop (PLL) and holding a previous PLL-wobble signal during atrack jump.

A third object of the present invention is to provide a track jumpmethod of generating a header mask signal using a signal that is notinfluenced by a wobble period during a track jump and for apredetermined period of time after the track jump.

In order to achieve the above objects, the present invention provides atrack jump method including the steps of receiving a track jump command;checking whether a current location is the end of a header area when thetrack jump command is received; standing by without performing a trackjump when the current location is not the end of the header area andperforming the track jump with inhibition of a PLL of a wobble signalwhen the current location is the end of the header area; and resumingthe PLL of the wobble signal when the track jump is completed.

The checking step determines an off-point of a header mask signalindicating a header area as the end point of the header area.

The PLL inhibiting step inhibits the PLL of the wobble signal and holdsa PLL-wobble signal to a value obtained before the track jump isperformed.

The PLL inhibiting step slices a sum of or a difference between opticalreflected signals from the optical recording medium at a certain levelto generate a header mask signal indicating a header area.

The PLL inhibiting step counts wobble signals subjected to the PLL togenerate a header mask signal indicating a header area.

The PLL resuming step counts wobble signals subjected to the PLL togenerate a header mask signal indicating a header area when the trackjump is completed.

The PLL inhibiting step inhibits the PLL of the wobble signal in asection in which a header mask signal is on.

The PLL resuming step terminates the track jump before a point at whicha header mask signal indicating a header area is turned on.

In another embodiment, a track jump method includes the steps ofreceiving a trackjump command; checking whether a current location isthe end of a header area when the track jump command is received; andperforming a track jump when the current location is the end of theheader area and standing by without performing the track jump until theheader area ends when the current location is not the end of the headerarea.

When an N-time consecutive track jump command is received, a procedureof starting the track jump at a falling edge of a header mask signal,ending the track jump before a rising edge of the header mask signal,and turning on a servo is repeated N times.

In still another embodiment, a track jump method includes the steps ofperforming a track jump with inhibition of a PLL of a wobble signal whena track jump command is received; and resuming the PLL of the wobblesignal when the track jump is completed.

In another embodiment, a track jump method includes the steps of maskinga header area using a first header mask signal indicating the headerarea during a track jump; and masking a header area using a secondheader mask signal indicating the header area during normalrecording/reproducing, wherein the first header mask signal is notinfluenced by a wobble period.

The first header mask signal is generated by slicing a sum of or adifference between optical reflected signals from the optical recordingmedium at a certain level.

The second header mask signal is generated by counting wobble signalssubjected to the PLL.

The track jump method further includes the step of masking a header areausing the first header mask signal until a wobble signal is normallydetected after the track jump is completed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will becomemore apparent by describing in detail preferred embodiments thereof withreference to the attached drawings in which:

FIG. 1 is a block diagram of a typical optical recording/reproducingapparatus;

FIGS. 2( a) through 2(c) are timing diagrams showing generation of aheader mask during a normal servo;

FIGS. 3( a) through 3(d) are timing diagrams showing a tracking errorsignal and a track zero crossing (TZC) signal in the case where a headerarea exists during a track jump performed in FIG. 1 and are timingdiagrams related to the track jump;

FIGS. 4( a) through 4(g) are timing diagrams showing the trackjumpperformed in FIG. 1;

FIG. 5 is a block diagram of a configuration for performing a trackjumpaccording to a first embodiment of the present invention;

FIG. 6 is a flowchart of a track jump according to the first embodimentof the present invention;

FIGS. 7( a) through 7(f) are timing diagrams for showing the processesof a track jump according to the present invention;

FIGS. 8( a) through 8(e) are timing diagrams of a tracking error signaland a TZC signal which are generated when N track jumps are performedavoiding a header area according to the first embodiment of the presentinvention, and are timing diagrams related to the track jump;

FIG. 9 is a block diagram of a configuration for performing a track jumpaccording to a second embodiment of the present invention;

FIG. 10 is a flowchart of a trackjump according to the second embodimentof the present invention; and

FIGS. 11( a) through 11(c) are timing diagrams for showing the processesof a trackjump according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is characterized by that a track jump is performedat a falling point of a header mask signal to avoid a header area, and atrack jump operation is held before the falling point even if a trackjump command is generated. The header mask signal indicates the headerarea. Various methods of detecting a header area and generating a headermask signal have been proposed. A header mask signal may be generatedusing a phase locked loop (PLL)-wobble signal which is generated bysubjecting a wobble signal formed in wobbling shape on a track to a PLL.Alternatively, a header mask signal may be generated using a readchannel 1 signal or a read channel 2 signal.

In a first embodiment of the present invention, during a track jump, awobble signal is inhibited from being subjected to a PLL, a previousPLL-wobble signal is held, and a header mask signal is generated usingthe held PLL-wobble signal.

In a second embodiment of the present invention, during a track jump, aheader mask signal is generated using a read channel 1 signal or a readchannel 2 signal, and after completion of the track jump, a header masksignal is generated using a PLL-wobble signal.

In the present invention, it is assumed that a header area is defined bya “high” level of a header mask signal, and a data recordable area isdefined by a “low” level of the header mask signal. The falling point ofthe header mask signal indicates the end of a header area.

First Embodiment

FIG. 5 is a block diagram showing a configuration for performing a trackjump method according to the first embodiment of the present invention.Only portions related to the track jump are illustrated.

Referring to FIG. 5, the configuration includes an optical disc 201 towhich data can be rewritten, an optical pickup (P/U) 202 for recordingand reproducing information to and from the optical disc 201, a radiofrequency (RF) and servo error generator 203 for generating an RF (or aread channel 1) signal and servo error signals, such as a read channel 2signal, a tracking error signal and a focus error signal from anelectric signal output from the P/U 202, a sample and hold unit 204 forholding the tracking error signal and the focus error signal, which aregenerated by the RF and servo error generator 203, in a header area, aservo controller 205 for individually processing the focus error signaland the tracking error signal, which have been held or bypassed by thesample and hold unit 204, to generate a focus driving signal and atracking driving signal, a microcomputer 206 for controlling a trackjump, a servo signal generator 207 for generating a header mask (H/M)signal and an L/G switching signal and controlling a PLL of a wobblesignal according to a jump hold signal J_hold output from themicrocomputer 206, a wobble PLL unit 208 for inhibiting a wobble signalfrom being subjected to a PLL and holding a previous PLL-wobble signalaccording to a hold signal Hold output from the servo signal generator207, a focus servo driver 209 for receiving the focus driving signalfrom the servo controller 205 and driving a focus actuator within theP/U 202, and a tracking servo driver 210 for receiving the trackingdriving signal from the servo controller 205 and driving a trackingactuator within the P/U 202.

When a track jump is performed in the first embodiment of the presentinvention having such configuration, the microcomputer 206 checks afalling point of a header mask signal output from the servo signalgenerator before outputting a track jump control command to the servocontroller 205.

When a falling edge of the header mask signal is not detected, themicrocomputer 206 holds the track jump control command until the fallingedge is detected and outputs the track jump control command to the servocontroller 205 when the falling edge of the header mask signal isdetected.

The microcomputer 206 detects a track zero crossing (TZC) signal whichis turned on/off at a zero cross point of the tracking error signalinput through the servo controller 205 and outputs it to themicrocomputer 206. The microcomputer 206 uses the TZC signal as areference signal for controlling a kick pulse, brake pulse and a braketime during a track jump.

The microcomputer 206 also generates a jump hold signal J_hold forinhibiting a wobble signal from being subjected to a PLL and holding aprevious PLL-wobble signal during a track jump and outputs it to theservo signal generator 207. When receiving the jump hold signal J_hold,the servo signal generator 207 outputs a hold signal Hold to the wobblePLL unit 208.

The servo signal generator 207 also outputs the hold signal Hold to thewobble PLL unit 208 during a normal servo, that is, during normalrecording/reproducing, when a header area is detected.

The wobble PLL unit 208 generates a PLL-wobble signal by subjecting awobble signal recorded on an actual disc to a PLL and outputs thePLL-wobble signal to the servo signal generator 207. During thisoperation, when the hold signal Hold is received from the servo signalgenerator 207, the wobble PLL unit 208 stops the PLL of the wobblesignal and outputs a PLL-wobble signal that is held to a value obtainedbefore the track jump operation to the servo signal generator 207.

The servo signal generator 207 counts PLL-wobble signals output from thewobble PLL unit 208, generates a header mask signal H/M and aland/groove switching signal L/G, and outputs them to the microcomputer206.

FIG. 6 is a flowchart of an operation according to the present inventionwhen the track jump command is input, and FIGS. 7( a) through 7(f) aretiming diagrams during the operation.

When a disc is a rewritable disc, particularly, a digital versatile discrandom access memory (DVD-RAM), FIGS. 7( a) through (f) show an exampleof a forward 2 track jump. In the case of a DVD-RAM, since data can berecorded on both land and groove tracks, two tracks are jumped duringone period of a tracking error signal generated during a track jump, asshown in FIG. 7( a).

More specifically, when a track jump command is input in step 301, theservo signal generator 207 counts PLL-wobble signals output from thewobble PLL unit 208, generates a header mask signal, and outputs it tothe microcomputer 206. In step 302, the microcomputer 206 checks afalling point of the header mask signal output from the servo signalgenerator 207 before performing a track jump, that is, before outputtinga track jump control command to the servo controller 205. The fallingpoint of the header mask signal is checked for the purpose of making aTZC signal not be influenced by a header during the track jump.

Accordingly, when a falling edge of the header mask signal is notdetected in step 302, the track jump control command is held until thefalling edge is detected. When the falling edge of the header masksignal is detected, as shown in FIG. 7( c), the microcomputer 206outputs the track jump control command to the servo controller 205, andsimultaneously, outputs a jump hold signal J_hold in a “high” state, asshown in FIG. 7( d), to the servo signal generator 207 in step 303. Inthe present invention, it is assumed that the jump hold signal J_hold isin a “high” state during a track jump.

When receiving the jump hold signal J_hold in a “high” state, the servosignal generator 207 outputs a hold signal Hold in a “high” state to thewobble PLL unit 208. Here, it is assumed that the hold signal Hold forinhibiting a wobble PLL is in a “high” state.

Meanwhile, the servo signal generator 207 outputs the hold signal Holdto the wobble PLL unit 208 when a header area is detected during normalrecording/reproducing. In other words, the servo signal generator 207ORs the jump hold signal J_hold, as shown in FIG. 7( d), and the headermask signal H/M, as shown in FIG. 7( c), and outputs the result ofORing, as shown in FIG. 7( e), to the wobble PLL unit 208.

The wobble PLL unit 208 subjects a wobble signal recorded on a disc to aPLL to generate a PLL-wobble signal and outputs the generated PLL-wobblesignal to the servo signal generator 207. During this operation, whenthe hold signal Hold in a “high” state, as shown in FIG. 7( e), is inputfrom the servo signal generator 207, the wobble PLL unit 208 stops thewobble PLL operation of subjecting the wobble signal recorded on thedisc to the PLL. Then, the wobble PLL unit 208 outputs a PLL-wobblesignal which is held to a previous value, that is, a value obtainedbefore reaching a header area in the case of a normal servo or a valueobtained before performing a track jump, to the servo signal generator207. Accordingly, the PLL-wobble signal does not elongate and has aregular period during a track jump.

When the falling edge of the header mask signal is detected as describedabove, the microcomputer 206 outputs the jump hold signal J_hold to theservo signal generator 207, and simultaneously, checks a direction of atrack jump for starting the trackjump in step 304. In other words, it isdetermined whether a track jump is performed from an inner track to anouter track or from an outer track to an inner track.

When the trackjump direction is determined in step 304, a kick pulse isgenerated toward the track jump direction and applied to a trackingactuator in step 305. When the kick pulse is generated in step 305, thespeed of the tracking actuator increases, and an objective lens of thetracking actuator is pushed toward the track jump direction byacceleration of the tracking actuator. At this time, a TZC signal isdetected.

Next, a brake pulse is applied to the tracking actuator at a rising edgeof the TZC signal for a predetermined brake time to decelerate thetracking actuator in step 306. When the previously set brake time haselapsed, a tracking servo and a sled servo are turned on in step 307. Inparticular, the tracking servo and the sled servo are turned on afterthe track jump starts and before the header mask signal rises.

When the tracking servo and the sled servo are turned on step 307, themicrocomputer 206 outputs the jump hold signal J_hold in a “low” state,as shown in FIG. 7( d), to the servo signal generator 207 in step 308.

When a falling edge of the jump hold signal J_hold is detected, theservo signal generator 207 outputs the hold signal Hold in a “low” stateto the wobble PLL unit 208. Accordingly, when the falling edge of thehold signal Hold is detected, the wobble PLL unit 208 resumes a PLL of awobble signal. In other words, holding of the PLL-wobble signal isinterrupted, and an actual wobble signal is subjected to a PLL. Then,the wobble PLL unit outputs a PLL-wobble signal to the servo signalgenerator 207.

When it is determined that the track jump fails to reach a target trackin step 309, the progress returns to the step 302, and the track jump iscontinued.

As described above, since the present invention starts a track jumpavoiding a header area, a TZC signal is not influenced by a header, asshown in FIG. 7( b). Accordingly, the TZC signal does not lead or lagbehind a desired location during the track jump. In addition, the pulsesof the TZC signal according to what is described are not generatedduring the track jump. Consequently, an exact and stable track jump isachieved.

The present invention holds a PLL-wobble signal during a track jump toprevent the PLL-wobble signal from elongating during the track jump,thereby exactly generating a header mask signal in a header area afterthe track jump is completed. Accordingly, a header coming first afterthe track jump can be stably masked, thereby preventing a tracking errorfrom being greater in a header area. Therefore, track slippage orunstable track servo can be prevented.

FIGS. 8( a) through 8(e) show waveforms when a 2-track jump isconsecutively performed N times. The track jump is performed avoiding aheader area as described above.

In other words, the track jump is started in synchronization with thefalling edge of a header mask signal. Then, the 2-track jump iscompleted before a rising edge of the header mask signal, and then aservo is turned on. This procedure is repeated N times.

Second Embodiment

FIG. 9 is a block diagram showing a configuration for performing a trackjump method according to the second embodiment of the present invention.Only portions related to the track jump are illustrated.

Referring to FIG. 9, the configuration includes an optical disc 401 towhich data can be rewritten, an optical pickup (P/U) 402 for recordingand reproducing information to and from the optical disc 401, a RF andservo error generator 403 for generating a RF signal (or a read channel1 signal R-ch1) and servo error signals such as a read channel 2 signalR-ch2, a tracking error signal TE and a focus error signal FE from anelectric signal output from the P/U 402, a sample and hold unit 404 forholding the tracking error signal and the focus error signal, which aregenerated by the RF and servo error generator 403, in a header area, aservo controller 405 for individually processing the focus error signaland the tracking error signal, which have been held or bypassed by thesample and hold unit 404, to generate a focus driving signal and atracking driving signal, a microcomputer 406 for controlling a trackjump according to the present invention, a first header mask (H/M)signal generator 407 for generating a first header mask signalindicating a header area using the read channel 1 signal or the readchannel 2 signal, which is output from the RF and servo error generator405, a wobble PLL unit 408 for subjecting a wobble signal output fromthe RF and servo error generator 403 to a PLL and outputting aPLL-wobble signal, a second H/M signal generator 409 for countingPLL-wobble signals output from the wobble PLL unit 408 and generating asecond header mask signal indicating a header area, a H/M controller 410for outputting either of the first header mask signal and the secondheader mask signal to the sample and hold unit 410 under control of themicrocomputer 406, a focus servo driver 411 for receiving the focusdriving signal from the servo controller 405 and driving a focusactuator within the P/U 402, and a tracking servo driver 412 forreceiving the tracking driving signal from the servo controller 405 anddriving a tracking actuator within the P/U 402.

FIG. 10 is a flowchart of an operation according to the secondembodiment of the present invention when a track jump command is input,and FIGS. 11( a) through 11(c) are timing diagrams during the operation.

Like the first embodiment, when a disc is a rewritable disc,particularly, a DVD-RAM, FIGS. 11( a) through 11(c) show an example of aforward 2 track jump. In the case of a DVD-RAM, since data can berecorded on both land and groove tracks, two tracks are jumped duringone period of a tracking error signal generated during a track jump, asshown in FIG. 11( a).

When a track jump is performed in the second embodiment of the presentinvention having such configuration, the microcomputer 406 outputs atrack jump control command to the servo controller 405. When the trackjump control command is input, the servo controller 405 detects a TZCsignal which is turned on/off at a zero cross point of a tracking errorsignal and outputs it to the microcomputer 406 in step 501. Themicrocomputer 406 uses the TZC signal as a reference signal forcontrolling a kick pulse, brake pulse and a brake time during the trackjump.

The microcomputer 406 switches a header mask mode J_mode in step 502.More specifically, the microcomputer 406 switches the header mask modeJ_mode to a “high” state and outputs the switched J_mode to the H/Mcontroller 410 in order to use a header mask signal generated by thefirst H/M generator 407.

In this embodiment, the H/M controller 410 selects a first header masksignal generated by the first H/M generator 407 when the J_mode is in a“high” state and selects a second header mask signal generated by thesecond H/M generator 409 when the J_mode is in a “low” state. Theselected header mask signal is output to the sample and hold unit 404.

Here, the first H/M generator 407 may generate a header mask signalusing a read channel 1 signal or a read channel 2 signal. For example,the header mask signal can be generated by slicing the read channel 1signal or the read channel 2 signal at a certain level. In addition,when a header mask signal is not influenced by a wobble period, theheader mask signal can be used as the first header mask signal.

Meanwhile, when the header mask mode J_mode is switched to the “high”state, the microcomputer 406 generates a kick pulse toward a track jumpdirection and applies it to a tracking actuator in step 503. When thekick pulse is generated in step 503, the speed of the tracking actuatorincreases, and an objective lens of the tracking actuator is pushedtoward the track jump direction by acceleration. At this time, a TZCsignal is detected.

Next, a brake pulse is applied to the tracking actuator at a rising edgeof the TZC signal for a predetermined brake time to decelerate thetracking actuator in step 504. When the previously set brake time haselapsed, a tracking servo and a sled servo are turned on in step 505.

When the tracking servo and the sled servo are turned on step 505, it isdetermined whether a target track is reached in step 506. When it isdetermined that the target track is not reached, the progress returns tothe step 503, and the above processes are repeated. When it isdetermined that the target track is reached, it is determined whether aPLL-wobble signal is normally and stably detected in step 507.

When it is determined that the PLL-wobble signal is not normallydetected in step 507, a header mask signal H/M and a focus error signalFE are held using the first header mask signal until the PLL-wobblesignal is normally detected. When the PLL-wobble signal is normallydetected after a predetermined time has elapsed, the header mask modeJ_mode is toggled from a “high” state to a “low” state in step 508. Inother words, the header mask mode J_mode is switched to the “low” state,and the switched header mask mode J_mode is output to the H/M controller410 in order to use a header mask signal generated by the second H/Mgenerator 409. In another example of step 508, an enough time tocompensate for elongation of the PLL-wobble signal is previously set,and a header mask mode J_mode is switched to a “low” state after thepreviously set time has elapsed.

Accordingly, the present invention can exactly generate a header masksignal in a header area after the track jump is completed, as shown inFIG. 11( c). In other words, a header coming first after the track jumpcan be stably masked, thereby preventing a tracking error from beinggreater in a header area, as shown in FIG. 11( a). Consequently, trackslippage or an unstable track servo can be prevented, thereby allowingdata to be recorded or reproduced in a stable servo.

Meanwhile, in the second embodiment of the present invention, themicrocomputer 406 may check a falling point of the header mask signaloutput from the H/M controller 410 before performing a track jump, thatis, before outputting a track jump control command to the servocontroller 405 for the purpose of making a TZC signal not to beinfluenced by a header during the track jump. After a track jump commandis input, when a falling edge of the header mask signal is not detected,the track jump control command is held until the falling edge isdetected. When the falling edge of the header mask signal is detected,the microcomputer 406 outputs the track jump control command to theservo controller 405, thereby starting the track jump.

In addition, to prevent a PLL-wobble signal from elongating, a wobblePLL in which an actual wobble signal is subjected to a PLL may beinhibited, and a PLL-wobble signal may be held to a value obtainedbefore the track jump is performed, during the track jump. For thisoperation, when a track jump command is input, the microcomputer 406outputs a hold signal Hold to the wobble PLL unit 408, and the wobblePLL unit 408 inhibits or resumes a wobble PLL according to the holdsignal Hold. When a header area is detected during a normal servo, thatis, during normal recording/reproducing, the microcomputer 406 alsooutputs the hold signal Hold to the wobble PLL unit 408.

Accordingly, the wobble PLL unit 408 outputs the PLL-wobble signal, inwhich a wobble signal recorded on an actual disc is subjected to thePLL, to the second H/M generator 409. During this operation, when thehold signal Hold is received from the microcomputer 406, the wobble PLLunit 208 stops the PLL of the wobble signal. Then, the wobble PLL unit408 outputs a PLL-wobble signal which is held to a previous value, thatis, a value obtained before reaching a header area in the case of anormal servo or a value obtained before performing the track jump, tothe second H/M signal generator 409.

As described above, in a track jump method according to the presentinvention, once a track jump command is input, a track jump operation isheld until a falling edge of a header mask signal is detected. The trackjump starts at the falling edge of the header mask signal and endsbefore a rising edge of the header mask signal so that a TZC signal isnot influenced by a header during the track jump. Therefore, the trackjump can be exactly and stably performed. In particular, when the trackjump command is input, a PLL of a wobble signal is inhibited, and aPLL-wobble signal is held to a previous value obtained before the trackjump is performed, during the track jump. Therefore, a header comingfirst after the track jump is completed can be stably masked, therebypreventing a system from being unstable due to a header during the trackjump. In addition, once the track jump command is input, a header masksignal is generated using a read channel signal which is not influencedby a wobble period, until a wobble signal becomes stable after a trackjump. During a normal servo, a header mask signal is generated using aPLL-wobble signal to mask a header area. Therefore, a header area comingfirst after the track jump is completed can be stably masked, therebypreventing a system from being unstable due to a header during the trackjump.

The foregoing embodiments are merely exemplary and are not to beconstrued as limiting the present invention. The present teachings canbe readily applied to other types of apparatuses. The description of thepresent invention is intended to be illustrative, and not to limit thescope of the claims. Many alternatives, modifications, and variationswill be apparent to those skilled in the art.

1. A track jump method for an optical recording medium on which aplurality of header areas having different phases are disposed betweendata areas, the method comprising: (a) checking whether a currentlocation is the end of a header area when a track jump command isreceived; and (b) starting the track jump when the current location isthe end of the header area, wherein a header mask signal masking theheader area is generated using a read channel 1 signal or read channel 2signal irrespective of a wobble signal during a track jump and aftercompletion of the track jump the header mask signal is generated using aphase locked loop-wobble signal.
 2. A method of claim 1, wherein thetrack jump is completed before a rising edge of the header mask signal.3. A track jump method for an optical recording medium on which aplurality of header areas having different phases are disposed betweendata areas, the method comprising: (a) checking whether a currentlocation is the end of a header area when a track jump command isreceived; and (b) determining whether to start the track jump based onthe checking step (a), wherein a header mask signal masking the headerarea is generated using a read channel 1 signal or read channel 2 signalirrespective of a wobble signal during a track jump and after completionof the track jump the header mask signal is generated using a phaselocked loop-wobble signal.
 4. An apparatus for controlling a track jumpfor an optical recording medium, the apparatus comprising: a pickup; anda controller to check whether a current location of the pickup is an endof a header area, wherein a header mask signal masking the header areais generated using a read channel 1 signal or read channel 2 signalirrespective of a wobble signal during a track jump and after completionof the track jump the header mask signal is generated using a phaselocked loop-wobble signal.
 5. A track jump method for an opticalrecording medium on which a plurality of header areas having differentphase are disposed between data areas, the method comprising: (a)masking the header areas using a first header mask signal generated by areflected signal irrespective of a wobble signal and indicating theheader areas of the optical recording medium during the track jump; (b)masking the header areas using a second header mask signal generated bythe wobble signal during normal recording/reproducing.
 6. A method ofclaim 5, further comprising: (c)checking whether a current location isthe end of the header area by a falling edge of a header mask signalwhen a track jump command is received; and (c) starting the track jumpwhen the current location is the end of the header area.
 7. A method ofclaim 5, wherein the first header mask signal is generated by slicing asum of or a difference between optical reflected signals from theoptical recording medium at a certain level.
 8. A method of claim 5,wherein the second header mask signal is generated by counting wobblesignals subjected to the phase locked loop.
 9. A method of claim 5,further comprising the step of masking the header areas using the firstheader mask signal until the wobble signal is normally detected afterthe track jump is completed.